1. Field
The present invention relates to the field of content security. More particularly, this invention relates to a system and method for providing conditional access to incoming digital content.
2. Background Description
For many years, there has been a growing demand for electronic systems providing visual and/or audible content to consumers. Typically, content providers have supplied consumers with content in a variety of forms (e.g., movies, television programming, etc.). When transmitted in an analog format such as the National Television Systems Committee (NTSC) or Phase Alternating Line (PAL), formats, the content is somewhat protected due to the inherent nature of analog signaling. For example, analog content is troublesome to illicitly copy and redistribute. Also, the recorded copies have poorer image quality than the original content. On occasion, copy protection signals may be added to the content in order to inhibit its successful recordation by a video cassette recorder.
Over the last decade, there has been a growing demand for digital content. In set-top boxes, such as Digital Satellite System (DSS.TM.) boxes by Sony Corporation of Tokyo, Japan, content is received in a digital format and is converted into an analog format prior to display or playback. This analog content possesses the same inherent protective nature as described above. Prior to conversion to an analog format, the digital content may be encrypted.
Recently, original equipment manufacturers (OEMs) are providing open, re-programmable digital platforms as part of the electronic system. For example, set-top computers (e.g., WEB TV.TM.) are currently being sold in the market to receive content, such as Internet Protocol (IP) commands, download image(s), audio and the like. Unfortunately, these digital platforms render both hardware and software, including security applications, observable and modifiable by an unauthorized user or a malicious program. This threat has greatly impeded the expansion of digital content distribution because there is no adequate mechanism to protect content providers from unauthorized copying and distribution of their digital content.
In an attempt to mitigate unauthorized copying of digital content, certain electronic systems now are implemented with a receiver having a removable smart card that controls the flow of content. A "smart card" is a form factor similar to a credit card, but includes an integrated circuit (IC) instead of a magnetic strip. The IC provides one or more parameters used for identification and possibly for decryption of digital content provided from a remote transmission source. As a result, smart cards provide a conditional access mechanism to mitigate illicit access to digital content due to their replaceable nature.
To protect the digital content, it may be appropriate to redistribute replacement smart cards to subscribers of the electronic system if one of two conditions occurs; namely, (i) a predetermined time period has elapsed; or (ii) the global cryptographic key used by every electronic system has been uncovered. However, this redistribution of smart cards poses a number of disadvantages. For example, one disadvantage is that continued supply of replacement smart cards is costly to both content providers and subscribers. Another disadvantage is that this technique is subject to increased distribution costs as the number of attempts to circumvent electronic systems increase and as the number of subscribers increases each year. Yet another disadvantage is that many subscribers may experience a loss of services upon failing to receive replacement smart cards in a timely manner.
Therefore, it would be desirable to create an electronic system operating in accordance with conditional access without the disadvantages described above.